Circular knitting machines

ABSTRACT

A multifeed circular knitting machine having a circular saw coupled to a welting dial and a knife seated upon the saw for cutting a yarn withdrawn from knitting. There is also a suction tube for holding a cut yarn. At one feed there is a guide for an elastomeric thread. A holder for the knife is slidable up and down in a bracket. When the knife is raised there is a space between it and the saw. But when the holder is released the knife moves down to cooperate with the saw. A cam on a control drum controls the holder. With the knife raised, a withdrawn elastomeric thread is first carried round on the saw past the knife element without being cut. The knife is then restored to its operative position. The thread is thereafter cut and held only after having been carried round a distance substantially in excess of that between the thread guide and the cutting and holding location.

United States Patent Grewcock et a1.

[ 1 Feb. 15,1972

[54] CIRCULAR KNITTING MACHINES [73] Assignee: Barber 8: Nicholls Limited, Burbage, Nr.

Hinckley, England [22] Filed: Apr. 20, 1970 [21] Appl.No.: 30,028

[56] References Cited UNlTED STATES PATENTS Dusik et al ..66/145 5 Lawson ..66/l72 E Primary Examiner-Wm. Caner Reynolds Attorney-Larson, Taylor and Hinds [57] ABSTRACT A multifeed circular knitting machine having a circular saw coupled to a welting dial and a knife seated upon the saw for cutting a yarn withdrawn from knitting. There is also a suction tube for holding a cut yarn. At one feed there is a guide for an elastomeric thread. A holder for the knife is slidable up and down in a bracket. When the knife is raised there is a space between it and the saw. But when the holder is released the knife moves down to cooperate with the saw. A cam on a control drum controls the holder. With the knife raised, a withdrawn elastomeric thread is first carried round on the saw past the knife element without being cut. The knife is then restored to its operative position. The thread is thereafter cut and held only after having been carried round a distance substantially in excess of that between the thread guide and the cutting and holding location.

3 Claims, 10 Drawing Figures CIRCULAR KNITTING MACHINES This invention relates to multifeed circular knitting machines of the kind which have a rotary needle cylinder and includes (a) a yarn or thread changing mechanism at each feed comprising a group of movable yarn or thread guides or feeders selectively operable to feed selected yarns or threads to and withdraw the same from the needles, according to requirements, and (b) a yarn severing and holding, i.e., trapping," mechanism having scissorlike knife elements and a suction tube of a pneumatic system respectively functioning to cut and hold a withdrawn yarn or thread until next required.

Although the invention is not necessarily limited in this respect, it is principally the intention to apply it to a circular hosiery knitting machine of the general kind referred to but also of the particular type equipped not only with a welting dial furnished with a circular series of dial jacks for the production of double or roll welts, but also with a yarn-severing device comprising, in combination, a flat, ringlike saw coupled to and rotatable together with the welting dial, said saw having sharpened sawteeth formed right around its periphery, and a sharpened knife element adapted to seat upon the flap upper surface of the rotary saw and to cooperate with relevant sawteeth in the severance of yarns or threads as and when they are withdrawn from knitting.

Thus, as well known to those skilled in knitting technology, whenever on a hosiery machine of the type just described, a double or roll welt is to be made, knitted loops, of course, are transferred from the needles to, and temporarily held by, the dial jacks while knitting of the welt proceeds, whereupon the held loops are transferred back to the needles to complete the welt of folded fabric. Moreover, in such a machine the rotary saw and the knife element cooperable therewith are common to all of the feeds: thus, whenever a yarn or thread is withdrawn from knitting as a consequence of a selected yarn guide or feeder, previously in its feeding position, being moved into its nonfeeding position, a length of the withdrawn yarn or thread will be automatically caught into a space between to sawteeth and thereby swept by the rotating saw beneath the knife element at which point the yarn or thread will be severed by the cooperative scissorlike action of the sharpened edge of the relevant sawtooth and the operative edge of the knife element seated upon it.

The invention is particularly concerned with a method of knitting integrally on to or into a circularly knitted article, or portion of circularly knitted fabric, an elasticated welt, band or segment incorporating courses or part courses knitted of an elastic or elastomeric thread.

Heretofore, when attempting to do this on a circular knitting machine of the kind herein referred to, the severed end of an elastic or elastomeric thread withdrawn from knitting immediately contracted and as a consequence became too short to be satisfactorily sucked into and held within the pneumatic trapper tube.

Naturally, this disability made it practically impossible to incorporate into circular knitted fabric courses, or part courses, of an elastic or elastomeric thread. The result of this disability was that when it was previously required to provide a circularly knitted article with, say, an elasticated welt it was necessary, as a separate operation, to sew on to the article a portion of separately produced elastic web.

Accordingly, the primary object of the present invention is to provide, in a circular knitting machine of the kind herein referred to, simple, relatively inexpensive and efficient yarn or thread severing means designed to obviate the foregoing dif ficulty.

A particular air is to provide specific practical yarn or thread severing means for this purpose in a circular hosiery machine of the particular type hereinbefore described, thereby enabling stockings, tights and similar articles to be produced with integrally knitted elasticated welts, garter bands and panels.

Yet another object is to provide in a circular knitting machine either of the general kind or of the particular type herein referred to, improved means for securely interlacing with circularly knitted fabric the leading end of the elastic or elastomeric thread as and when this is introduced and fed to needles by the relevant guide or feeder.

According to the characteristic feature of this invention, a circular knitting machine of the kind herein referred to is provided with means, operable at predetermined times by or from the machine control, for temporarily rendering inoperative a knife element of the yarn severing and holding mechanism, thereby enabling an elastic or elastomeric thread. as and when it is withdrawn from knitting to be first idly carried round past the said knife element and to be subsequently cut and held only after having been carried round to an extent substantially in excess of the distance between the elastic or elastomeric thread guide or feeder and the yarn or thread severing and holding location, during which extra travel of the thread the temporarily inoperative knife element is restored into its operative position.

The idea is that by virtue of having been idly carried round and additional distance, the eventually severed free end of the withdrawn elastic or elastomeric thread will be substantially longer than it would otherwise have been and thereby enabled to be sucked further into the pneumatic suction tube and hence satisfactorily held.

In order that the invention may be more clearly understood and readily carried into practical effect, a specific constructional example of the yarn or thread severing and holding mechanism provided thereby, as applied to an eight-feed circular hosiery machine of the particular type concerned, and the manner in which the yarn or thread severing device operates will now be described with reference to the accompanying diagrammatic drawings, wherein,

FIG. 1 is a front view principally of the head of the said knitting machine, showing the yarn or thread severing device in position thereon and also the part of the control drum of the machine from which the knife element, cooperable with the rotary ringlike saw, is operated,

FIG. 2 is a plan view corresponding to FIG. 1 showing all of the eight feeds, and the control drum in dotted lines,

FIG. 3 is a side view of the connections through the medium of which the knife element is operated at the dictates of the control drum,

FIG. 4 is a vertical sectional view of so much of the head of the knitting machine as is necessary to show the guide or feeder which carries the elastic thread in its out position and the said thread being taken from the needles by the rotary saw, this view also depicting the end trimmer plate, the knife element and the suction tube of the pneumatic system,

FIG. 5 is a plan view similar to FIG. 4 but showing the elastic thread after it has been idly carried round by the saw past the inoperative knife element to the extent of one complete revolution of the knitting head,

FIG. 6 is a general perspective view of the yarn severing and pneumatic holding mechanism, with the knife element lifted and the elastic thread, withdrawn from knitting, in the course of being carried by the rotating saw past the said element in its inoperative, i.e., raised, position,

FIG. 7 is a view similar to FIG. 6 but illustrating the elastic thread at the instant of being cut by the knife element which is shown in its operative down position cooperating with the saw,

FIG. 8 is a detail vertical sectional view of the knife element and the sawtaken on the line VIIIVIII of FIG. 5,

FIG. 9 is a detail elevational view of the cam layout at a feed-showing also one of the knitting needles employed and the manner in which needle butts of different lengths are selectively acted upon by the cams in the production of the particular elasticated structure concerned, and

FIG. 10 is a plan view of the bolt-clearing cam included in FIG. 9,

Like parts are designated by similar reference characters throughout the drawings.

In FIGS. 1-3, the main frame of the eight-feed circular hosiery knitting machine is designated FR. Within the back part of this frame, below and at the rear of the knitting head KI-I, is mounted the intermittently rotatable and conventional control drum CD ofthe machine.

The positions of the eight feeds of the machine are indicated at F --F". At each such feed there is provided a yarn or thread changing mechanism of quite usual form comprising a group of individually pivoted yarn or thread guide or feeders ll, 1 1 and 11 (see FIG. selectively operable from an intermittently turnable drum 12 which is furnished with prearranged selector bits 13. These bits are suitably set out for action selectively upon lugs 14 on the said guides or feeders. As shown in FIGS. 4 and 5, each drum 12 has rigidly secured to ti a ratchet wheel 15 cooperable with a pawl 16. This pawl is pivotally mounted upon an actuating lever 17 which in turn rocks freely about the rotational axis of the drum 12. The actuating lever 17 is forked at 17a (FIG. 4) for engagement with a pin 18 on a lever 19 controlled, through the medium of a Bowden cable 20, from the control drum CD. In each of FIGS. 4 and 5, and elastic thread guide or feeder 11 at the second feed F is shown in its out, i.e., nonfeeding, position to withdraw the elastic thread ET from knitting. The guide or feeder 11 on the other hand, is shown in its in" position feeding a yarn Y to the needles. At each feed, moreover, there is provided a feed plate 21 furnished with poteyes 22 through which yarns or threads from supply packages are guided.

As regards the knitting head KI-I, this basically comprises a rotary needle cylinder 23 equipped with a circular series of knitting needles 24 each of the form illustrated at the righthand side of FIG. 9. Surrounding the upper end of the needle cylinder 23 is a tricked sinker ring 25 equipped with a circular series of outside sinkers such as 26 (see FIG. 4) cooperable with the needles 24. Located concentrically within and at the upper end of the needle cylinder 23 is a conventional welting dial 27 (FIGS. 4 and 8) which is mounted upon a vertical spindle 28 arranged to be motor driven through drive-transmitting means (not shown) housed within an encasement 29.

The yarn-severing device with which the illustrated machine is equipped comprises, in combination, a flat ringlike saw 30 which is mounted upon, coupled to and rotatable together with the welting dial 27, said saw having sharpened sawteeth 300 right around its periphery, and a sharpened knife element 31 adapted, when operative, to seat upon the flap upper surface of the rotary saw 30, in the manner depicted in FIG. 7, and to cooperate with sawteeth in the severance of yarns or threads as and when they are withdrawn from knitting. As will be seen in FIGS. 6, 7 and 8 the saw 30 has a vertically disposed annular flange 30b.

The yarn or thread holding component of the mechanism is constituted by a suction tube 32 which may be made of copper and is incorporated in a pneumatic system. The open end 320 of the tube 32 is shaped as shown in FIGS. 6 and 7, its lower edge being spaced a little above and parallel to a fixed horizontal end trim plate 33 of brass located within the confines of the vertical annular flange 30b of the rotary saw 30.

In accordance with the characteristic feature of the present invention, and as shown most clearly in FIG. 8, the knife element 31 is pivotally mounted within a forked lower end 340 of a vertically disposed rodlike holder 34 which in turn is slidably mounted for movement up and down within a cylindrical portion 35a of a bracket 35. The latter is attached, by means of a screw 36, upon the top of a carrier 37 which is supported, adjustably, upon the top of a raised portion 33a of the brass end trim plate 33. To prevent any turning movement of the holder 34 during vertical movements thereof upwardly and downwardly, the said holder is provided with an outwardly directed pin 38 which is guided in a vertical slot 35b cut in the cylindrical portion 35a of the bracket 35.

The holder 34 and hence also the knife element 31 carried thereby are movable upwardly to the position shown in FIG. 6 to provide a clear space between the cutting edge of the knife element and the rotary saw 30, thereby rendering the said element inoperative. The knife element and its holder are also movable downwardly to enable the element to resume its operative position in cooperable contact with the top of the saw 30 as illustrated in FIG. 7. These movements of the knife element are controlled from cams, such as 39, on the control drum CD, through the medium of intermediate connections of any suitable character. In the illustrated example, these connections consist of a rocking lever 40 and a Bowden cable 41 which connects an arm 40a of this lever with the upper end of the rodlike knife holder 34. Another arm 40b of the lever 40 is formed with a toe 40c adapted to be acted upon by the control cams 39. The lever 40 is suitably influenced by a tension spring 42 arranged as shown in FIG. 3. A compression spring 43, surrounding the relevant end of the Bowden cable 41, is interposed between the upper end of the knife holder 34 and the underside of the mainly closed top of the cylindrical portion 35a of the bracket 35 (see FIG. 8). By virtue of this arrangement, whenever the toe 40c is lifted by a cam 39 the knife element 31 will be raised against the combined action of the tension spring 42 and the compression spring 43. Conversely, whenever the toe 40c drops off a cam 39, the knife element 3] will be released for downward movement into contact with the rotary saw 30 under the combined influence of these two springs.

The knife element 31 is raised, and thereby rendered temporarily inoperative, whenever the elastic thread ET is withdrawn from knitting by raising the guide or feeder 11 at the feed F into the position shown in FIG. 4. Preferably, and as shown by a comparison of FIG. 6 with FIG. 7, the rendering inoperative of the knife element 31 and its eventual restoration into its operative position are so timed as to enable the withdrawn elastic thread ET to be carried idly round to the extent of one complete revolution of the knitting head KH in addition to the distance between the guide or feeder II and the yarn or thread severing location, i.e., the knife element 31.

To support and guide the elastic thread ET as it is idly carried round by the saw 30 (with the knife element 31 raised), the brass end trim plate 33, 33a has soldered thereinto a plurality of vertical pins 44, 45, 46, 47, 48 and 49. As will be seen more clearly in FIG. 4, the pin 48 is cranked at 480 so as to prevent the elastic thread ET, as it is wound around the pins, from riding up and becoming disengaged therefrom. The precise number of pins is not important. Moreover, the relative dispositions of these pins is not critical except in so far as the first pin 44 must be actually located beneath the open end 32a of the suction tube 32 so as to ensure that an elastic thread, when cut, is sucked up the said tube at a location where the suction is most powerful.

In FIG. 6, the relevant end of the withdrawn elastic thread ET is shown as having been caught between teeth 30a of the rotating saw 30 and carried thereby around the first two pins 44 and 45 of the series and beneath and past the raised knife element 31. The winding of the thread ET around all of the pins and twice around the pins 44 and 45 is depicted in FIG. 7. Whilst, for this purpose, the saw 30 is in the course of making just over one complete revolution, the knife element 31 is restored into its operative position for cooperation with the saw so that by the time the described amount of winding is complete, the thread ET will be automatically cut in the manner and at the point C shown in FIG. 7. The now relatively long and released free end of the elastic thread will at this stage he instantaneously unwound off the pins and sucked up safely into the suction tube 32. A portion of the sucked-up end is indicated in chain lines at ET in FIG. 7.

According to another aspect of the invention the leading end portion of an elastic or elastomeric thread, when introduced and fed to needles by virtue of the relevant guide or feeder being moved into its feeding position, is securely locked into the fabric by causing the first few needles which take the yarn to tuck; in this way the said leading end of the elastic or elastomeric thread is interlaced with the fabric.

To elasticate a welt, band, segment or panel of circular knitted fabric, the elastic or elastomeric thread is knitted into the fabric in predeterminately spaced wales of suitable spaced courses, the said yarn floating across those wales in which it is not knitted. Experience has shown that advantageous results are obtained by knitting the elastic or elastomeric thread or alternate needles only in every third course in the elasticated portion although there is no limitation in this respect. That is to say, in the advantageous construction just mentioned all the needles of the machine are caused to knit plain loops of a main, e.g., crepe, yarn for two courses, then a l l course of elastic or elastomeric thread is knittedfollowed by two more plain courses of the main yarn, and so on.

In carrying out the invention on an eight-feed circular hosiery machine equipped with 400 needles, feeds F, F and F may be out of action during the knitting of an elasticated welt or band, in which instance the main yarn may be knitted at feeds F, F, F and F and feed F may, as shown, be reserved for the elastic or elastomeric thread which is knitted on 200 of the needles. Alternatively, the lastmentioned yarn may be fed in at feed F or F with feed F out of action.

To enable this particular elasticated structure to be produced, the needles, or their actuating jacks or sliders, as the case may be, are furnished with respectively different lengths of butts, viz, those associated with the few needles which are required to tuck to lock in an elastic or elastomeric thread have butts of an intermediate length, those associated with the alternate needles which are to knit the elastic or elastomeric thread have long butts and those associated with intervening needles which are to miss and avoid knitting the said thread have relatively short butts. In conjunction with the butts of the different lengths, there is provided, at the feed at which the elastic or elastomeric thread is fed in, a bolt cam which although stepped to present a ledge corresponding with tucking height is nevertheless adapted to raise long butts to clearing height, this cam being radially movable into different positions, according to the specified knitting requirements. All this is exemplified in FIGS. 9 and 10.

Thus, each of the needles in the illustrated machine is like that depicted at the right-hand side of FIG. 9. As will be seen, the needle is provided at its lower extremity with an operating butt of one of the three lengths shown. That is to say, those butts B on needles which are to tuck are of an intermediate length; those butts B on needles which are to knit the elastic thread are long ones and those butts l3 on intervening needles which are to avoid knitting the thread are relatively short ones. One but of each of the three lengths just mentioned is shown in FIG. 10.

In conjunction with butts of these three different lengths there is provided at the feed F in the illustrated machine a radially movable bolt cam 50. This cam, although stepped to present a ledge 500 corresponding with tucking height TH, is nevertheless adapted to raise long butts B to clearing height CH. The cam 50 is radially movable into different positions, according to knitting requirements, and when so moved into an appropriate position misses the short butts B so that the latter pass by at the low level LL (FIG. 9). When the said cam is moved fully in, as shown in full lines in FIG. 10, it acts on butts of all three lengths.

At 51 and 52 in FIG. 9 are respectively represented the stitch cam and the upthrow cam both associated with the adjustable clearing cam at the feed.

The invention is particularly useful in forming elasticated welts on the upper ends of a pair of initially separate long stockings the inner sides of the thigh portions of which are suitably cut and seamed together to form tights. The cut and seamed welts thus together provide a band of elastication right around the upper margin of the tights to fit the wearers waist.

We claim:

1. A circular knitting machine comprising, in combination: a rotary needle cylinder; a circular set of knitting needles in said cylinder; a multiplicity of feeds at each of which needles can be caused to take yarn and knit; a yarn-changing mechanism at each feed having a group of movable yarn guides selectively operable to feed selected yarns to and withdraw the same from the needles and the yarn-changing mechanism at one feed having a uide for an elastomeric thread; a rotary welting dial locate within the circle of needles and furnished with a circular series of dial jacks for the production of double welts; a yarn-severing device comprising a flat ringlike saw coupled to and rotatable together with the welting dial, said saw having sharpened sawteeth formed right around its periphery, and a sharpened knife element adapted to seat upon the flat upper surface of the rotary saw and to cooperate with relevant sawteeth in the severance of yarns as and when they are withdrawn from knitting; and a yarn-holding device in the form ofa suction tube ofa pneumatic system,

said severing and holding device respectively functioning to cut and hold a withdrawn yarn until next required; wherein the improvement resides in the provision of a holder for the said knife element which is slidable up and down in a bracket, and is both movable upwardly to provide a clear space between its cutting edge and the rotary saw, thereby rendering the knife element inoperative, and also releasable to permit it, with a downward movement, to resume its operative position in cooperable contact with the top of the saw, the timing of the specified upward and downward movements of the knife element being controlled, in relation to an upward movement of the elastomeric thread guide to withdraw an elastomeric thread from knitting, by cams on a control drum of the machine through intermediate connections, said timing being such that the withdrawn elastomeric thread, with the knife element temporarily rendered inoperative at the relevant time is first idly carried around on the saw past the knife element without being cut, to the extent of one complete revolution of the knitting head in addition to the distance between the elastomeric thread guide and the thread-severing location, and is then cut and held at this location by restoration of the temporarily inoperative knife element into its operative position during the described additional travel of the said withdrawn thread.

2. A multifeed circular knitting machine according to claim 1, wherein there is mounted above the rotary knitting head a relatively fixed end trim plate which is furnished with a plurality of upstanding thread supporting and guiding pins around which the elastomeric thread is wound when carried round past the knife element.

3. A multifeed circular knitting machine according to claim 2, wherein the bracket in which the holder for the knife element is slidable is mounted upon the end trim plate. 

1. A circular knitting machine comprising, in combination: a rotary needle cylinder; a circular set of knitting needles in said cylinder; a multiplicity of feeds at each of which needles can be caused to take yarn and knit; a yarn-changing mechanism at each feed having a group of movable yarn guides selectively operable to feed selected yarns to and withdraw the same from the needles and the yarn-changing mechanism at one feed having a guide for an elastomeric thread; a rotary welting dial located within the circle of needles and furnished with a circular series of dial jacks for the production of double welts; a yarn-severing device comprising a flat ringlike saw coupled to and rotatable together with the welting dial, said saw having sharpened sawteeth formed right around its periphery, and a sharpened knife element adapted to seat upon the flat upper surface of the rotary saw and to cooperate with relevant sawteeth in the severance of yarns as and when they are withdrawn from knitting; and a yarnholding device in the form of a suction tube of a pneumatic system, said sEvering and holding device respectively functioning to cut and hold a withdrawn yarn until next required; wherein the improvement resides in the provision of a holder for the said knife element which is slidable up and down in a bracket, and is both movable upwardly to provide a clear space between its cutting edge and the rotary saw, thereby rendering the knife element inoperative, and also releasable to permit it, with a downward movement, to resume its operative position in cooperable contact with the top of the saw, the timing of the specified upward and downward movements of the knife element being controlled, in relation to an upward movement of the elastomeric thread guide to withdraw an elastomeric thread from knitting, by cams on a control drum of the machine through intermediate connections, said timing being such that the withdrawn elastomeric thread, with the knife element temporarily rendered inoperative at the relevant time is first idly carried around on the saw past the knife element without being cut, to the extent of one complete revolution of the knitting head in addition to the distance between the elastomeric thread guide and the threadsevering location, and is then cut and held at this location by restoration of the temporarily inoperative knife element into its operative position during the described additional travel of the said withdrawn thread.
 2. A multifeed circular knitting machine according to claim 1, wherein there is mounted above the rotary knitting head a relatively fixed end trim plate which is furnished with a plurality of upstanding thread supporting and guiding pins around which the elastomeric thread is wound when carried round past the knife element.
 3. A multifeed circular knitting machine according to claim 2, wherein the bracket in which the holder for the knife element is slidable is mounted upon the end trim plate. 